Cleaning apparatus

ABSTRACT

A cleaning device for an electrostatographic imaging surface, is provided with an endless loop cleaner transported in sweeping contact with an electrostatographic imaging surface from which it is desired to remove electrostatically adhering toner. An electrical biasing potential is applied to the endless loop, said biasing potential being of sufficient magnitude and polarity to attract toner from the surface to the cleaning means. A pick-off means is positioned in proximity with the cleaning means and in turn has applied thereto an electrical biasing potential of a magnitude and polarity sufficient to attract toner from the cleaning means to the pick-off means. Toner which is removed from the cleaning means by the pick-off means may then be placed in a convenient receptacle. More specifically, the means for applying the electrical biasing potential is in the form of a corona generating device located within the loop and positioned opposite the area of sweeping contact of the imaging surface with the cleaning means. A cleaning means is provided, preferably in the form of a fiber pile sheet or belt, and the pick-off means includes a pick-off forming device in the form of a roller which is of such a diameter as to cause the fiber pile of the cleaning means to exhibit a spreading or opening effect sufficient to allow a corresponding pick-off roller to remove toner from a deep position within the fiber pile.

United States Patent 11 1 Roth et al.

1 1 CLEANING APPARATUS [75] Inventors: Charles F. Roth, Monroe, N.Y.;

Gordon C. Butler, Welwyn Garden City, England [73] Assignee: XeroxCorporation, Rochester, N.Y.

[22] Filed: Apr. 27, 1973 [21] Appl. No.: 354,962

Primary E.\uminerHarvey C. Hornsby Assistant Examiner-C. K. MooreAttorney, Agent, or FirmJames J. Ralabate; Earl T. Reichert [57]ABSTRACT A cleaning device for an electrostatographic imaging surface,is provided with an endless loop cleaner trans- 1 1 Apr. 29, 1975 portedin sweeping contact with an electrostatographic imaging surface fromwhich it is desired to remove electrostatically adhering toner. Anelectrical biasing potential is applied to the endless loop, saidbiasing potential being of sufficient magnitude and polarity to attracttoner from the surface to the cleaning means. A pick-off means ispositioned in proximity with the cleaning means and in turn has appliedthereto an electrical biasing potential of a magnitude and polaritysufficient to attract toner from the cleaning means to the pick-offmeans. Toner which is removed from the cleaning means by the pick-offmeans may then be placed in a convenient receptacle. More specifically,the means for applying the electrical biasing potential is in the formof a corona generating device located within the loop and positionedopposite the area of sweeping contact of the imaging surface with thecleaning means. A cleaning means is provided, preferably in the form ofa fiber pile sheet or belt, and the pick-off means includes a pick-offforming device in the form of a roller which is of such a diameter as tocause the fiber pile of the cleaning means to exhibit a spreading oropening effect sufficient to allow a corresponding pick-off roller toremove toner from a deep position within the fiber pile.

12 Claims, 4 Drawing Figures CLEANING APPARATUS This invention relatesto electrostatographic imaging systems and, more particularly, to animproved apparatus for cleaning electrostatographic imaging surfaces.

The formation and development of images on an imaging surface byelectrostatographic means is well known. One basic process, as taught inU.S. Pat. No. 2,297,691, by C. F. Carlson involves placing a uniformelectrostatic charge on an imaging surface such as a photoconductiveinsulating layer, exposing the layer to a light-and-shadow image todissipate the charge in the areas of the layer exposed to the light anddeveloping the resulting electrostatic latent image by depositing on theimage a finely divided electroscopic material referred to in the art astoner. The toner is normally attracted to those areas of the layer whichretain a charge, thereby forming a toner image corresponding to theelectrostatic latent image. This toner image may then be transferred toa support surface such as paper, and the transferred image maysubsequently be permanently affixed to the support surface. Aftertransfer, the residual toner remaining on the layer is removed by acleaning operation and the layer may then be employed for anotherimaging cycle.

As is well known in recent years, the steadily increasing size ofvarious industries has required an enormous increase in the amount ofpaper work that must be accomplished, maintained, and made available forwide circulation. In present day commerical automaticcopiers/reproduction machines, the electrostatographic imaging surface,which may be in the form of a drum or belt, moves at high rates in timedunison relative to a plurality of processing stations. This rapidmovement of the electrostatographic imaging surface has required vastamounts of toner to be used during development.

Associated with the increased amounts of toner is the difficulty inremoving the residual toner image remaining on the imaging surface aftertransfer. in the reproduction process of Carlson as described above, theresidual image is tightly retained on the photoconductive layer by aphenomenon that is not fully understood but believed to be caused by anelectrical charge and van der Waalls forces that prevents completetransfer of the toner to the support surface, particularly in the imagearea. The residual toner image is normally removed by cleaning devicessuch as a brush type cleaning apparatus or web type cleaning apparatus.A typical brush cleaning apparatus is disclosed in-U.S. Pat. No.2,832,977 to L. E. Walkup et al. and in U.S. Pat. No. 2,91 1,330 to H.E. Clark. The brush-type cleaning means usually comprises one or morerotating brushes which brush toner from the photoconductive surface intoa stream of air which is exhausted through a filtering system. A typicalweb cleaning device which retains toner is disclosed in U.S. Pat. No.3,186,838 to W. P. Graff, Jr. et al.

While ordinarily capable of cleaning electrostatographic imagingsurfaces, conventional cleaning devices have not been entirelysatisfactory. Most of the known cleaning devices usually become lessefficient as they become contaminated with toner which cannot be removednecessitating frequent replacement of the cleaning device. As a result,valuabletime is lost during down time-while a change is being made. Afurther problem is that cleaning devices employed in current commericalcopier/duplicator machines permanently remove residual toner particlesfrom the system. Since toner is an expensive consumable, permanentremoval of the residual toner particles from the system during cleaningis undesirable because it adds to the cost of machine operation. Boththe web-type and brush cleaning units normally do not return residualtoner particles to be reusable as developer after the cleaning operationdue to the collection of lint from the web or brush. Furthermore, thecleaning operation can result in generation of heat resulting inphysical and chemical changes in the toner. In addition, an elaborateand noisy vacuum and filtering system is necessary to collect theresidual toner particles removed by the brush. Moreover, large amountsof toner particles thrown into the air by the rapidly rotating brushcleaner often drift from the brush cleaning housing and form unwanteddeposits on critical machine parts.

While the web-type cleaner has some advantages, it is difficult to alignwith the surface of the electrostatographic imaging surface, and unevencontact between the web on a takeup roll is often encountered even withcomplex alignment apparatus. Another problem with the web-type cleaneris that pressure contact between cleaning webs and some imaging surfacesmust be kept to a minimum to prevent destruction of the imaging surface.

in U.S. Pat. No. 3,580,673 to F. Y. Yang, there is disclosed anothertype of cleaning device employing a brush roller contacting the imagingsurface, and wherein magnetic beads are intermixed with toner particlesand subjected to an attractive bias force which aids in dislodging theresidual toner image. However, although the use of magnetic beadsaccomplishes an cleaning function, it is more desirable to effect andefficient cleaningoperation without the use of additional particulatematerial. In U.S. Pat. No. 3,572,923 to D. J. Fisher, opposite biasingis employed to attract particles from a brush roller which contacts theimaging surface to remove residual toner. Both of the foregoing systems,although improving toner removal by means of electrostatic forces,require a brush roller engaged in frictional contact with the imagingsurface. a

It has been found, however, that the use of brush rollers result incertain difficulties. Specifically, mechanical interference of thefibers forming the interference surface of a brush roller with theimaging surface is greater than is required only for a cleaning action.The extra interference built into the spacing between a roller and animaging surface is designed to compensate for machine tolerances such asrun out and for fiber matting. It is a normal tendency for fibers afterrepeated interference with an imaging surface to form a mat or abent-over position which results in reduction of the interferencebetween the brush roller and the imaging surface, thereby changing themechanical action pick-off roller, the result will be increased mattingdue to the heavy interference. In addition, as relative humidity andfiber conductivity change, electrostatic conditions of the fibersthemselves will change. Electrostatic charge on the fibers will dependto a large degree upon the triboelectric relationship of the fibers andthe imaging surface; Conduction from cleaning and toner removal biasingalso influencefiber charges and these factors are further influenced byenvironmental conditions. Since brush cleaning by means of electrostaticbiasing requires placement of a charge on the brush at some point priorto its interferring relationship with an imaging surface, the transitionbetween the application of the charge and actual interference will causea change in the electrostatic charge placed on the fiber due to'variation inthe triboelectric relationship between the' fibers andphotoreceptors caused by such environmental conditions. Thus, there is acontinuing need for an improved system for cleaning electrostatographicimaging surfaces.

It is therefore, an object of this invention to provide a method andapparatus for cleaning electrostatographic imaging surfaces whichovercome the abovenoted' deficiencies.

It is another object of this invention to improve the quality of printsproduced by electrostatographic reproduction machines.

his a' further object of this invention to reduce toner consumption inautomatic electrostatographic imaging machines.

' apparatus and reproduction equipment which does not require extensivealignment or adjustment.

It is another object of this invention to remove residual toner forimmediate reuse in an electrostatographic imaging machine.

It is a further object of this invention to provide a simple,inexpensive and reusable apparatus for cleaning electrostatographicimaging surfaces.

It is still a further object of this invention to provide a cleanin gapparatus for an electrostatographic imaging machine which is moreefficient than existing cleaning devices. 7

It is still a further object of this invention to prevent powder cloudformation as a result of a toner particle dispersion at the cleaningstation of an electrostatographic imaging machine. I

It is another object of this invention to reduce noise level of anelectrostatographic imaging machine. It is another object of thisinvention to substantially reducethe effects of fiber matting in acleaning device employed with an electrostatographic imaging machine. v,

It is another object of this invention to provide a cleaning device foran electrostatographic imaging machine employing fiber interference forcleaning an imaging surface with improved removal of toner from the rootareas of the fiber.

It is another object of this invention to provide a cleaning device foran electrostatographic imaging machine which will be relativelyinsensitive to environmental conditions.

The foregoing objects of the present invention are achieved by anendless loop cleaning means transported in sweeping contact with anelectrostatographic imaging surface from which! it is desired to removeelectrostatically adhering toner. An-electrical biasing potential isapplied to the endless loop, said biasing potential being of sufficientmagnitude and polarity to attract toner from the imaging surface to thecleaning means. A pick-off means is positioned in proximity with thecleaning means and in turn has applied thereto an electrical biasingpotential of a magnitude and polarity sufficient to attract toner fromthe cleaning means to the pick-off means. Toner which is removed fromthe cleaning means by the pick-off means may then be placed in aconvenient receptacle. More specifically, the means for applying theelectrical biasing potential is in the form of a corona generatingdevice located within the loop and positioned opposite the area ofsweeping contact of the imaging surface with the cleaning means. Acleaning means is preferably in the form of a fiber pile sheet or belt,and the pick-off means includes a pick-off forming device which is ofsufficient diameter to cause the fiber pile of the cleaning means toexhibit a spreading or opening effect sufficient to allow acorresponding pick-off roller to remove toner from a deep positionwithin the fiber pile.

The foregoing objects and brief description of the present invention aswell as other objects and further features thereof will become moreapparent from the following more detailed description and appendeddrawings wherein:

FIG. 1 is a partial schematic and cross-sectional side elevational viewof a cleaning apparatus as employed in conjunction with a form ofelectrostatographic imaging device employing an endless loopphotoreceptor;

FIG. 2 is a detail of the pick-off mechanism of FIG.

FIG. 3 is a perspective illustration of the operation'of the inventionemploying a fiber pile sheet and recycling device; and,

FIG. 4 shows an alternative embodiment of the present inventionemploying transversely movable endless belts.

Referring to FIG. 1 there is shown a typical apparatus for reproducing astationary planar original document supported at an object plane on atransparent platen. For purposes of this explanation, the reproductionmedium is illustrated as an imaging surface formed as an endless looprecycling photoreceptor 10 such as an electrostatographic plate formedas an endless belt moving in the direction indicated. For purposes ofthis invention, the particular form of imaging surface may take theshape of either a drum or endless loop photoreceptor or the like, itbeing immaterial for purposes of this invention which form is used. Theimaging surface 10, which can, for example be a reusable or nonreusablephotoreceptor such as selenium or zinc oxide or phthalocyanine in abinder, comprises for the purposes of this embodiment a recycling web ofdurable flexible and preferably electrically conductive materialsupporting on its outer surface a thin layer of photoconductiveinsulating material. Any suitable photoconductive insulating materialknown in connection with electrostatographic plates may be employed,such as, for example, a thin layer of vacuum deposited vitreousselenium. Selenium, as well as other photoconductor insulating materialscoated on a flexible support may be repeatedly bent around a radius of afew inches without cracking or flaking from the support and withoutremoving electrostatographic effectiveness. Cylindrical rollers l2, l4and 16 support the imaging surface 10 in the form of an endless flexiblebelt and motor 18 drives the roller 14 about its shaft 20, whereby theimaging surface is continually advanced at a uniform constant rate.

As is well known in electrostatographic processes, the imaging surface10 in the course of its movement is first charged by means of a coronacharging device 22 supported adjacent to the imaging surface to effect auniform high potential thereon of the order of several hundred volts.After the imaging surface 10 has transversed the charging device 22, itadvances planarly between rollers 12 and 14 to an exposure stationillustrated generally as 24 for exposure to a pattern of light andshadow as may be provided in conventional manner. One example of a meansor mode of applying a light and shadow pattern is illustrated in U.S.Pat. No. 3,432,231 to J. F. Gardner. The exposure of the imaging surface10 to the light image discharges the photoconductive layer in the areastruck by light so that there remains on the imaging surface anelectrostatic latent image configuration corresponding to the lightimage projected by the device 24. As the imaging surface continues itsmovement around the roller 14, the latent electrostatic image passesthrough a developing station 26 at which a suitable mechanism appliesdeveloping material to the imaging surface as it passes therethrough.Typical of devices for applying developing material is shown in U.S.Pat. 2,618,552 to Edward N. Wise and U.S. Pat. No. 2,638,416 to Walkupand Wise. Thereafter, the powder image passes through an image transferstation designated generally as 28 at which the powder image iselectrostatically transferred to a copy web 30 by means of a secondcorona charging device 32.

The support surface through which the powder image is transferred may bepaper, vellum, cardstock, etc. The web 30 is supported by rollers 34 and36, the latter being driven by a suitable motor driving unit 38. Theimage may then be fixed to the support web by any suitable means such asthe heat fuser unit 40, as disclosed, for example in U.S. Pat. No.2,852,651 to Crumrine and to the aforesaid U.S. Pat. No. 3,432,231. Itwill be understood that instead of winding onto a pick-up roller 36, thesupport web 30 may be passed directly to a cutter or the like by whichthe web is cut into separate lengths, or the web itself may constitute aseries or plurality of individual sheets of suitable support surfacematerial such as individual sheets of paper and the like which areperiodically provided to the station 28.

The foregoing explanation of the reproduction system employing anendless loop photoreceptor as an imaging surface is provided asexemplary in conjunction with the use of the present invention, it beingunderstood that a drum-type of electrostatographic imaging surface couldbe used, such as that shown and described in U.S. Pat. No. 3,301,126 toOsborn et a1.

After image transfer, the movement of the imaging surface 10 carries thenow residual image pattern to a cleaning station illustrated generallyas 42. The heart of the cleaning device 42 is an endless loop cleaningmeans 44 which is shown in the form of a continuously recycling belt.The belt is composed of a fiber pile 46 which, as shown in FIG. 2,includes a backing member 48 and a plurality of upstanding cleaningfibers 50. The entire cleaning mechanism 42 is secured into a housing,not shown, which is, in turn, secured to the machine frame.

The continuously recycling belt 44 is adapted for rotation by means of aplurality of rollers. Thus, motivation is supplied to a tension trackingand drive roller 52 adapted for rotation about a shaft 54 which isjournaled for rotation in the housing and is driven in the directionindicated by the arrow by means of a motor 56. The roller 52 is employedfor driving since the configuration shown in FIG. 1 permits the belt 44to exhibit a large degree of wrap about the roller 52, and maximumfrictional contact is derived therewith by choosing a frictional coatingfor roller 52. The tracking featu're is provided by shaping the side ofthe roller 52 with a crown which will thus provide accurate tracking ofthe belt 44 during rotation as is well known. The belt is brought intoproximity with the imaging surface 10 by means of suitably positioned.forming roller 56 and 58 each respectively adapted for rotation abouttheir central shafts which are in turn journaled for such rotation intothe external machine housing. A corona charging device 60 is positionedbetween the forming rollers 56 and 58 for purposes which will beexplained in further detail below. A pick-off mechanism, illustratedgenerally as 62 is provided by a pick-off forming a roller 64 and a mainpick-off roller 66, each also adapted for rotation about theirrespective central shafts, and in turn journaled for rotation into theexternal machine housing. As the path of the belt 44 continues from theforming roller 58 about the pick-off forming roller 64, it traverses afurther corona charging device 68. Another corona charging device ispositioned as shown between the roller 52 and the forming roller 56. Asshown, the roller 52 is adapted for lateral movement in theschematically illustrated slot 72 by means of a suitable screw or likeadjustment. Since the belt 44 is flexible, adjustment of the roller 52along the slot 72 results in an increase or decrease in tension of thebelt 44. Since the forming rollers 56 and 58 provide an arcuate path forthe belt 44 about the imaging surface 10 in accordance with the surfaceof the roller 12, adjustment of the position of the roller 52 in slot 72will result in an increase or decrease of tension of the belt 44 againstthe surface of the imaging surface 10.

For efficient wiping action, it is desirable that the fiber pile 46 ofthe belt 44 be driven in an opposite direction at the interferenceformed between the belt 44 and the surface 10 at speeds which may rangefrom about half to about three times the speed of travel of the belt 10.Alternatively, it is noted that the fiber pile of the belt 44 may bedriven in the same direction as the imaging surface 10, as long as therelative speeds of the surface 10 and the belt 44 are such that there issufficient relative motion to obtain the desired wiping action of thecleaning fibers on the surface 10.

Turning now to the operation of the invention, it is noted that forpositive to positive reproduction, a negatively charged toner isemployed whereas in a negative to positive reproduction a positivelycharged toner is employed. For purposes of explanation, it will beassumed that positive to positive reproduction is the mode of operationof the device, it being understood that either operation will be usablewith the present invention as will be apparent from the followingdescription.

Thus, negatively charged toner forming the residual image left on theimaging surface 10 after emergence from the transfer station 28 passesfrom the roller 16 towards the roller 12 beneath a corona chargingdevice 74 and a discharge lamp 76. The function ofthe corona chargingdevice 74 which is energized by adc source 74A, is to provide a slightlynegative charge to the toner in order to insure that;th e toner retainsitsnegative charge characteristicsprior-to entering the cleaning station42. Activation of the pre-clean lamp 76 serves to place the toner'andsurface 10 at approximately the same charge level in order to eliminateany attraction causedby any polarity difference between the toner andsurface 10. It should be noted that the corona charging device 74 anddischarge lamp 76 are not essential, their elimination being a functionof whether the residual toner retains sufficient negative charge tooperate in conjunction with the cleaning device 42. After cleariing,afurther corona charging device and discharge lamp may be located at astation A in order to neutralize any post cleaning residual charge.

As the negatively charged toner enters into the interference area formedbetween the belt 44 and the imaging surface 10, toner material isattracted by virtue of the electrostatic andtribo-electric field effectsto the fiber pile 46 of the belt 44. To this end, the corona chargingdevice 70, which has been energized by means of the electrical biasingpotential applied thereto from the dc biasing source 70A, has resultedin the placement of a positive charge on the fiber material 50. Coronacharging device 70 performs a post pick-off charge placement function,neutralizing any prior positive level of the biasing potential appliedto the charging device 70 serves to place a positive potential on thefiber material 50. As the belt 44 continues its traverse around thefirst'forming roller 56 it enters into proximity with the coronacharging device 60 which is in turn energized by a dc. source ofpotential 60A. The source of potential 60A provides a positive voltagelevel to the coratron unit 60 which in turn provides a positive biascharge to the backing 48 of the fiber pile 46. The resultant positivecharge on the fabric pile attracts the negatively charged toner materialinto the fibers 50 of thebelt 44. It is noted that since the coronacharging device 60 is used to supply the cleaning bias to the fiber pileby charging the backing 48, the placement of the corona charging device60 directly over the area of interference between the cleaning belt 44and the imaging surface 10, results in an intense cleaning fieldprovided with a relatively small current and little danger from arcing.

Thus, for example, the power supply 60A together with charging unit 60should bring the backing of the belt to, for example, 4,000 voltsrelative to ground, the polarity determined by materials used andconditions encountered. This will require the power supply 60A todeliver in the range of 1-3 p. amp/in. and have acoronode potentialadequate to avoid cut off. These values will depend on characteristicsof the corona charge unit and the power supply system as well as loadimpedance.

The backing 48 is itself a resilient high compliance material ofrelatively high impedance, such as 18 meg ohms, thus providing the highresistivity necessary to limit the current generated by the relativelyhigh volthigh potential enables the degree of interference between thefibers S and the imaging surface to be correspondingly reduced sincewiping action no longer becomes as critical as .in prior devices inorder to remove toner particles from the surface 10. The use of acontinuously recycling belt 44 permits the corona charging device 60 tobe placed directly opposite the area of interference within the loop,and thus enables the application of a relatively high charging field tobe applied to the belt backing 48 and thus to the fiber 50. It should benoted that the dc. source 60A may be varied and hence the voltageapplied to the corona charging device 60 selectively changed to obtainmost optimum operating conditions. Furthermore, resistivity of thebacking may be selected to accommodate a range.

of voltage supplied from the potential source 60A in accordance with thelimitation of current flow necessary in order to prevent any arcing fromoccurring between the corona charging device 60 and the imaging surface10. Fibers can support only so much potential longed as well asphotoreceptor wear reduced. Desirably, the cleaning fibers of the fiberpile 50 are made from any suitable nonconductive material which willfurther inhibit the arcing condition noted above. I

Typical cleaning fiber materials are acrylic velvets, orlon,polypropylene, nylon, rayon, acetates, mohair, Arnel, glass, Dynel,Dacron, cotton and other natural and synthetic fibrous or filamentarymaterials and mixtures thereof. In addition, in order to further enhancethe attraction of the toner to the cleaning fibers, the fibersmay bemade of or coated with a material having a triboelectric attraction forthe toner particles. Typical materials having this relationship aredescribed in US. Pat. No. 2,618,55l to Walkup; US. Pat. No. 2,618,552 toWise; U.S. Pat. No. 2,638,416 to Walkup and Wise; and US. Pat. No. R25,1 36 to Carlson. Typical backing materials are fabrics of woven nylon,polypropylene, cotton, etc. of adequate flex, strength and abrasionresistance. The fibers 50 are bonded or otherwise suitably attached tothe resilient backing, the base area of the fibers at its junction withthe backing being generally designatable as the root structure thereof.It should be noted that the feature of triboelectric attraction withregard to the cleaning fibers further enhances the attraction of tonerto the fiber belt, thereby further enhancing the advantages of thepresent invention. The cleaning fibers may extend any suitable lengthwhich may range from l/l6 of an inch to about 5/16 of an inch andpreferably about and eighth of an inch to about 3/ l 6 of an inch, for afiber density ranging from about 10,000 to about 100,000 and more fibersper square inch. Desirably, the interference between the cleaning fibersand the imaging surface will be just brushing contact. It should benoted that the attractive forces created with the intense cleaning biasfiled provided by the present invention would be sufficient to attractparticles without any contact; however, it has been found that thecleaning bias field in combination with slight brushing contact betweenthe fibers and the imaging surface serve to remove toner with maximumefficiency.

After removal of toner, the belt next passes around the forming roller58 and approachesthe pick-off station 62 and, in so doing ,.it traversesthe corona charging device 68 which is in turn biased by means of electrical biasing of potential applied for the dc. source 68A. The functionof coratron charging device 68 is to provide a pre pick-off charge tothe toner particles. To this end, the source 68A applies a negativepotential which may be in the range of between 1,000 to 3.000 volts, andmore desirably at about 1,500 volts. As a result, toner particles areprovided with a negative charge level prior to entering the nip betweenthe pick-off forming the roller 64 and the pick-off roller 66. Inaccordance with the invention, the pick-off forming roller 64 is coupledto a source of potential 64A which applies an electrical biasingpotential of a negative polarity to the pick-off forming roller 64. Thepick-off roller 66 is connected to the machine frame through its centralshaft which may be journaled to the machine frame housing for rotation.The main pick-off roller which may be of stainless steel or likeconductive material is at ground potential relative to the pick-offforming roller 64. Since, in this embodiment the toner particles afteremergence from beneath the corona charging device 68 are provided with anegative charge, the additional negative charge provided by the roller64 acts to repel the particles towards the relatively positive polarityof the main pick-off roller 66.

As a result of the repelling force, the toner particles are dislodgedfrom the fibers 50 and placed on the main pick-off roller 66. Aswasnoted in discussion of prior art devices, a great difficulty inremoving toner from fiber pile has been the necessity of removingparticles from as far down in the pile as possible in order to eliminatetoner build-up. As noted in FIG. 2, the present invention provides apick-off forming roller 64 of relatively small dimension. In thismanner, as the belt 44 approaches the nip area between the roller 64 andthe roller 50, the small diameter of the roller 64 causes the resilientbacking of the roller 48 to deform by making a relatively sharp traverseabout the forming roller 64 which causes the fibers of the fiber pile 46to separate by a distance sufficient to expose the root structure of thefiber pile 46. In this manner, toner particles indicated generally as 78are thus exposed to the repelling force provided by virtue of the tonerparticle negative charge and the negative charge placed upon the formingroller 64, causing repelling of the particles to the relativelypositively charged pick-off roller 66. Since the spreading of the fibers50 of the fiber pile 46 by virtue of the small diameter of the roller 64will result in separation, the effect will be to reduce the shielding ofeach fiber in the nip by virtue of the surrounding fibers therebyfurther improving the strength of the electrostatic field of generatedbetween the roller 64 and the roller 66.

The efficiency of removal will be a function of a combination offactors, including the diameter of the pickoff forming roller 64, thedepth of the fibers 50 and their density, the angle of wrap of thebacking 48 around the perimeter of the roller 64 and the strength of theelectrostatic field between the toner, the fiber pile 46, and thepick-off roller 66. These factors can each be adjusted relative to theother to maximize the efficiency of the cleaning operation in eachsituation.

The pick-off roller 66 is provided with a rotation in I the direction ofthe arrow in the same relative direction as the movement of the belt 44in the nip between the rollers 64 and 66. This rotation may be as aresult of the frictional contact between the fiber pile and the roller66, or it may be the result of an independent drive provided by aseparate motor unit coupled to the central shaft of the roller 66, notshown. It may be advantageous from a cleaning viewpoint to provideindependent drive to the roller 66 with a slightly higher velocity thanthe movement of the belt 44, thereby providing relatively clean surfacesof the roller 66 at the moment of removal of toner 78 from the fiberpile 46. In addition, matting forces exerted on the fiber pile 46 as aresult of engagement between the roller 64 and 66 may be reduced byproviding a separate drive to the roller 66 and spacing roller 66 fromthe fiber pile 46 such that only slight engagement of the fibers 50 andthe roller 66 occur. If the relative field strength is high enough,there may actually be a gap between the roller 66 and the upper portionof the fiber pile 46.

The rotation of the pick-off roller 66 will be such that toner particles78 will be carried about the surface of the roller until reaching theposition wherein the force of gravity may be sufficient to pull thetoner particles 78 from the roller 66. It should be noted that since theroller 66 is preferably at ground potential, and that the particles 78have a slightly negative charge, the toner particles will not normallyadhere to the surface of the roller 66 but will fall as aresult of thegravity attraction upon reaching a non-supported position caused by therotation of the roller 66. To further insure removal of the tonerparticles, a scraping assembly 80 may be positioned at an advantageouslocation relative to the surface of the roller 66 for wiping theparticles from the surface of the roller. Particles will then fall intoa suitable receptacle 82 which may include a lower portion 84 which willserve to recycle the toner particles falling thereon to the developingstation 26 where they may be reutilized in the developing process.

Referring to FIG. 3, the recycling mechanism is shown in some greaterdetail. With like reference numerals referring to like componentsrelative to FIG. 2, FIG. 3 illustrates an imaging surface 10 which isshown in FIG. 3 is in its alternative form as a photoreceptive layercoated on a drum rather than upon an endless loop as shon in FIG. 1. Theoperation of the device as shown in FIG. 3 is in all respects as shownin FIG. 1. As shown in FIG. 3, the pick-off roller 66 has coupledthereto a scraper or doctor blade assembly indicated generally as 80 andwhich comprises a blade member anchored with respect to the roller 66 byany suitable retaining means. As the pick-off roller 66 rotates, tonerwhich is adhering thereto can fall into the receptacle 82 or be scrapedtherefrom by means of the scraper assembly 80. As the toner is collectedin the receptacle 82, it is removed therefrom by means of an auger 86mounted for rotation on a shaft 88 and driven by suitable driving meansnot shown. The auger 86 rotates through the toner collected in thereceptacle 82 in a direction shown by the arrow towards one or moreconduits 90 from which the toner is discharged, as by gravity, andsubsequently conveyed as by a belt or the like for reuse at thedevelopment station as described above.

In the foregoing embodiment, the cleaning device has been shown as afiber pile sheet which coacts with the surface of the imaging surface inthe manner as described aforesaid. Referring now to FIG. 4, an alterna'tive embodiment is shown wherein the cleaning device is in the form of abelt of relatively narrow dimension.

In this embodiment, the belt moves transversely to the rotation of themoving imaging surface which as shown in FIG. 4 is in the configurationof a drum although it it to be understood that it may also be in theform of a continuous loop photoreceptor such as is shown in FIG. 1. Theoperational concept pertaining to the device as is described above inconnection with the fiber pile sheet is similar to that as described inconnection with the transversely moving belt.

As shown in FIG. 4, a belt 92 is constructed as a fiber pile with aflexible backing and cleaning fibers as described in connected with thesheet shown in FIG. 1. The belt isldriven by a series of rollersincluding first and second forining rollers 94 and 96, a pick-offforming roller'98, and a driving tension and tracking roller 100. Thedriving roller 100 includes a motor 102 coupled to the driving rollerfor supplying the necessary motive force. The belt 92 includes the fiberpile on the surface which will be facing outward against the surface ofthe drum. The belt is positioned with respect to the drum for aninterfering engagement. An elongated corona charging device 106 is shownalong the length of the belt 92 directly opposite the drum over the areaof interference of the belt and the drum. A corona charging deviceincludes a source of potential 106A for applying the electrical biasingpotential to the charging device 106 necessary to form the cleaning biasfield as described in connection with the embodiment of FIG. 1. Inorder: tolmaintain the belt 92 against the surface of theidrumduring itsentire period of interference, the coron a"chargi ng device 106 may beadapted to include a pluralityof skids which will apply pressure againstthe belt during its interference traverse. The additional coronacharging devices such as shown in FIG. 1 are applicable to the operationof the device as shown in FIG. 4 but have not been shown for purposes ofclarity.

The operation of the device shown in FIG. 4 is precisely that as thedevice shown in FIG. 1 with the exception that a transversely movingbelt is employed. In order to prevent saturation of the narrow widthbelt it is possible to employ a second belt 110 which as shown in FIG. 4is positioned just above the first belt and driven by means of commonshafts coupling complementary rollers at the same locations as thedrive, forming and pick-off rollers noted above. In this event, a commonpick-off roller 108 may be employed to dislodge toner particles-from thebelt 92 and the additional corresponding belt 110. As before, areceptacle 112 receives'the particles which are dislodged from the belts92 and 110 as well as the similar scraping mechanism 114 which may beemployed to dislodge particles which do not fall thereon of their ownaccord. To further improve the efficiency of the device, the drivemechanism 102 which intercouples a first driving roller 100 and a seconddriving roller 116 may be configured such that two rollers are driven inopposite directions, thereby enabling the two belts to move parallel toone another transverse to the drum in opposite directions and therebyfurther improving the cleaning effect. In this event, it would benecessary to rearrange the'polarity of the corona applied to therespective belts 110 and 92 at the various positions along its traversein order to allow the proper polarities to be set up in the fiber pilefor attraction and rejection of toner, as well as rearranging thecleaning stations.

The foregoing is thus a description of a new and novel cleaningapparatus capable of removing substantially all of the residual toner onthe surface of an electrostatographic imaging member. The use of theendless loop cleaning belt or sheet greatly improves the efficiency ofan electrostatographic imaging machine employing fiber rollers or thelike. The endless loop cleaning belt with a high compliance support forthe fiber pile allows for a combination of machine tolerances withlittle change in contact pressure. Since the contact pressure is aminimum necessary for proper cleaning action, no more than a minimummatting will occur. Thus, cleaning element life is prolonged andphotoreceptor wear is obviously reduced. Additionally, the accummulationof toner in the root area of the fiber pile cleaning material which hasheretofore necessitated greater interference by an electrostaticpick-off roller in order to expose toner to the electrostatic attractionof such roller, resulting in increased matting, is avoided by the use ofa small roll at the pick-off station to expose the root areas of thefiber, thereby permitting a lower interference profile in order topermit electrostatic attraction of toner from these lower areas of thefiber. Further, variations of environmental conditions resulting inelectrostatic changes in the fiber are no longer a problem since theelectrostatic charge on the cleaning fibers will no longer depend to alarge degree on the triboelectric relationship of the fibers andphotoreceptor. The present invention, in the creation of a very highintense cleaning field due to the positioning of a cleaning bias coronacharging device opposite the area of interference, permits the directapplication of an electrostatic charge far in excess of the normaltriboelectric relationship existing with prior art rollers and the likeand therefore to a large extent removes environmental conditions as thefactor causing a change in the triboelectric effect and therefore in thecleaning action.

Furthermore, the present invention permits accurate removal of tonerfrom the recording surface in such a manner that objectionable filmingof toner does not occur and hence the toner is adapted for repeatedreuse in the system. In addition, no powder cloud is formed in thecleaning station which undesirably can cause malfunction of themachinery. Furthermore, the cleaning apparatus of the present inventiondoes not require extensive repair, readjustment, replacement of rollers,dispensing of web, and the like. Thus, the apparatus of the presentinvention not only provides cleaning with greatly improved efficiencybut is also inexpensive and reusable and permits toner collected to beused repeatedly.

Although the invention has been described with reference to thestructures disclosed herein, it should not be confined to the detailsset forth since it is apparent that various modifications can be made.Thus, for example, the belt cleaning loops may be adapted to move atdifferent angular relationships with respect to the imaging surface, oradditional cleaning stations may be employed at desired locations aboutthe surface of the unit, and the entire operation of the device may beemployed for oppositely polarized toner material as in the case ofreversal development wherein a positively charged toner is employed. Inthis event, opposite polarities of coratron charging devices may beemployed to place the desired charges on the toner particles forappropriate movement. i

Other variations and changes will be obviously appar ent to thoseskilled in the art. It will be understood that the examples given in theembodiment shown are done so for purposes of illustration, and, that theinvention may be modified and embodied in various other forms withoutdeparting from the scope and spirit of the invention as disclosedherein.

What is claimed is:

1. Apparatus for removal of electrostatically adhering toner from anelectrostatic imaging surface in an electrostatic imaging devicecomprising an endless loop cleaning means formed of a fiber structure ona resilient backing transported over an area of interfering contact withsaid imaging surface, first means for applying an electrical biasingpotential to said cleaning means, said biasing potential being of amagnitude and polarity sufficient to provide an intense field acrosssaid interfering contact to thereby attract said toner from said surfaceto said cleaning means with a minimum of said interfering contact,pick-off means positioned in proximity with said cleaning means, secondmeans for applying an electric biasing potential to said pick-off means,said biasing potential being of a magnitude and polarity sufficient toattract said toner from said cleaning means to said pick-off means, andthird means'for receiving said toner from said pick-off means, saidpick-off means including a pick-off forming roller positioned withinsaid cleaning means, said pick-off forming roller being of a diametersufficient to cause said resilient backing to deform about said rolleruntil said fibers separate, exposing the root structure thereof, and apick-off roller coacting with the spread portion of said fiber pile forremoving toner from said root structure,

2. The apparatus of claim 1 wherein said cleaning means is an elongatedbelt of fiber pile material, and said first means includes a coronacharging device positioned within said cleaning means opposite said areaof interfering contact.

3. The apparatus of claim 1 wherein said pick-off roller is positionedopposite said pick-off forming roller and forming a nip with respect tosaid forming roller, said cleaning means passing therebetween, means forplacing a charge on said toner prior to entry into said nip, and saidsecond means applying said potential to said pick-off forming rollerwhereby said toner is repelled from said cleaning means to said pick-offroller.

4. The apparatus of claim 3 wherein said apparatus further includesmeans for applying a charging potential to said cleaning means prior toentrance of said cleaning means into said area of interfering contact,said charge potential being sufficient to neutralize charge applied bysaid second means.

5. The apparatus of claim 1 wherein said cleaning means and said imagingsurface are each driven with a relative motion therebetween, and whereinsaid cleaning means is a first and second elongated belt of fiber pile,and means for driving each of said belts in a direc tion transverse tothe direction of movement of said imaging surface across the area to becleaned.

6. The apparatus of claim 1 wherein said cleaning means and said imagingsurface are each driven with a relative motion therebetween, and whereinsaid cleaning means is a fiber pile sheet, and means for driving saidfiber pile sheet in a parallel plane relative to said imaging surfacebut with a differential surface speed.

' 7. The apparatus-of claim 5 wherein said belts are each driven inopposite directions across said area of interfering contact. g

8. Apparatus for removal of electrostatically adhering toner from animaging surface in an electrostatographic imaging device comprising anendless loop cleaning means having a resilient backing and a cleaningsurface of upstanding cleaning fibers, the cleaning surface beingadapted to be transported over an area of interfering contact with saidimaging surface, a corona charging device positioned within saidcleaning means opposite said area of interfering contact for applying anelectrical biasing potential to said cleaning means, said biasingpotential applied by said corona charging device being of a magnitudeand polarity sufficient to provide a field across said interferingcontact to thereby attract said toner from said surface to said cleaningmeans with a minimum of said interfering contact, pick-off meanspositioned in proximity to said cleaning means, second means forapplying an electric biasing potential to said pick-off means, saidbiasing potential applied by said second means being of a magnitude andpolarity sufficient to attract said toner from said cleaning means tosaid pick-off means, and third means for receiving said toner from saidpick-off means.

9. Apparatus for removal of electrostatically adhering toner from animaging surface in an electrostatographic imaging device comprising aplurality of endless loop cleaning means each having a resilient backingand a cleaning surface of upstanding cleaning fibers, the cleaningsurface of each cleaning means being adapted to be transported over anarea of interfering contact with said imaging surface, means for drivingsaid imaging surface in one direction, and means for driving each ofsaid cleaning means in a direction transverse to said one direction, acorona charging device positioned within at least one of said cleaningmeans opposite said area of interfering contact for applying anelectrical biasing potential to said one cleaning means, said biasingpotential applied by said corona charging device being of a magnitudeand polarity sufficient to provide a field across said interferingcontact to thereby attract said toner from said surface to said onecleaning means with a minimum of said interfering contact, pick-offmeans positioned in proximity to said plurality of cleaning means,second means for applying an electric biasing potential to said pick-offmeans, said biasing potential applied by said second means being of amagnitude and polarity sufficient to attract said toner from saidcleaning means to said pick-off means, and third means for receivingsaid toner from said pick-off means.

10. The apparatus of claim 8 wherein said pick-off means includes apick-off forming roller, said pick-off forming roller positioned withrespect to said cleaning means whereby the latter wraps around theperimeter of said roller sufficiently to exhibit a deformation of saidresilient backing and thereby spreading the fiber of said fiber pile andexposing the root structure thereof.

11. The apparatus of claim 10 wherein said pick-off means includes apick-off roller positioned opposite said pick-off forming roller andforming a nip with respect to said forming roller, said cleaning meanspassing therebetween, means for placing a charge on said toner prior toentry into said nip, and said second means applying said potential tosaid pick-off forming 15 16 roller whereby saidtoner is repelled fromsaid cleaning cleaning means into said area of interfering contact,means to Sam roller i said charge potential being sufficient toneutralize 12. The apparatus of claim 11 wherein said apparatus furtherincludes means for applying a charging potential to said cleaning meansprior to entrance of said charge applied by said second means.

1. Apparatus for removal of electrostatically adhering toner from anelectrostatic imaging surface in an electrostatic imaging devicecomprising an endless loop cleaning means formed of a fiber structure ona resilient backing transported over an area of interfering contact withsaid imaging surface, first means for applying an electrical biasingpotential to said cleaning means, said biasing potential being of amagnitude and polarity sufficient to provide an intense field acrosssaid interfering contact to thereby attract said toner from said surfaceto said cleaning means with a minimum of said interfering contact,pickoff means positioned in proximity with said cleaning means, secondmeans for applying an electric biasing potential to said pick-off means,said biasing potential being of a magnitude and polarity sufficient toattract said toner from said cleaning means to said pick-off means, andthird means for receiving said toner from said pick-off means, saidpick-off means including a pick-off forming roller positioned withinsaid cleaning means, said pick-off forming roller being of a diametersufficient to cause said resilient backing to deform about said rolleruntil said fibers separate, exposing the root structure thereof, and apick-off roller coacting with the spread portion of said fiber pile forremoving toner from said root structure.
 2. The apparatus of claim 1wherein said cleaning means is an elongated belt of fiber pile material,and said first means includes a corona charging device positioned withinsaid cleaning means opposite said area of interfering contact.
 3. Theapparatus of claim 1 wherein said pick-off roller is positioned oppositesaid pick-off forming roller and forming a nip with respect to saidforming roller, said cleaning means passing therebetween, means forplacing a charge on said toner prior to entry into said nip, and saidsecond means applying said potential to said pick-off forming rollerwhereby said toner is repelled from said cleaning means to said pick-offroller.
 4. The apparatus of claim 3 wherein said apparatus furtherincludes means for applying a charging potential to said cleaning meansprior to entrance of said cleaning means into said area of interferingcontact, said charge potential being sufficient to neutralize chargeapplied by said second means.
 5. The apparatus of claim 1 wherein saidcleaning means and said imaging surface are each driven with a relativemotion therebetween, and wherein said cleaning means is a first andsecond elongated belt of fiber pile, and means for driving each of saidbelts in a direction transverse to the direction of movement of saidimaging surface across the area to be cleaned.
 6. The apparatus of claim1 wherein said cleaning means and said imaging surface are each drivenwith a relative motion therebetween, and wherein said cleaning means isa fiber pile sheet, and means for driving said fiber pile sheet in aparallel plane relative to said imaging surface but with a differentialsurface speed.
 7. The apparatus of claim 5 wherein said belts are eachdriven in opposite directions across said area of inTerfering contact.8. Apparatus for removal of electrostatically adhering toner from animaging surface in an electrostatographic imaging device comprising anendless loop cleaning means having a resilient backing and a cleaningsurface of upstanding cleaning fibers, the cleaning surface beingadapted to be transported over an area of interfering contact with saidimaging surface, a corona charging device positioned within saidcleaning means opposite said area of interfering contact for applying anelectrical biasing potential to said cleaning means, said biasingpotential applied by said corona charging device being of a magnitudeand polarity sufficient to provide a field across said interferingcontact to thereby attract said toner from said surface to said cleaningmeans with a minimum of said interfering contact, pick-off meanspositioned in proximity to said cleaning means, second means forapplying an electric biasing potential to said pick-off means, saidbiasing potential applied by said second means being of a magnitude andpolarity sufficient to attract said toner from said cleaning means tosaid pick-off means, and third means for receiving said toner from saidpick-off means.
 9. Apparatus for removal of electrostatically adheringtoner from an imaging surface in an electrostatographic imaging devicecomprising a plurality of endless loop cleaning means each having aresilient backing and a cleaning surface of upstanding cleaning fibers,the cleaning surface of each cleaning means being adapted to betransported over an area of interfering contact with said imagingsurface, means for driving said imaging surface in one direction, andmeans for driving each of said cleaning means in a direction transverseto said one direction, a corona charging device positioned within atleast one of said cleaning means opposite said area of interferingcontact for applying an electrical biasing potential to said onecleaning means, said biasing potential applied by said corona chargingdevice being of a magnitude and polarity sufficient to provide a fieldacross said interfering contact to thereby attract said toner from saidsurface to said one cleaning means with a minimum of said interferingcontact, pick-off means positioned in proximity to said plurality ofcleaning means, second means for applying an electric biasing potentialto said pick-off means, said biasing potential applied by said secondmeans being of a magnitude and polarity sufficient to attract said tonerfrom said cleaning means to said pick-off means, and third means forreceiving said toner from said pick-off means.
 10. The apparatus ofclaim 8 wherein said pick-off means includes a pick-off forming roller,said pick-off forming roller positioned with respect to said cleaningmeans whereby the latter wraps around the perimeter of said rollersufficiently to exhibit a deformation of said resilient backing andthereby spreading the fiber of said fiber pile and exposing the rootstructure thereof.
 11. The apparatus of claim 10 wherein said pick-offmeans includes a pick-off roller positioned opposite said pick-offforming roller and forming a nip with respect to said forming roller,said cleaning means passing therebetween, means for placing a charge onsaid toner prior to entry into said nip, and said second means applyingsaid potential to said pick-off forming roller whereby said toner isrepelled from said cleaning means to said pick-off roller.
 12. Theapparatus of claim 11 wherein said apparatus further includes means forapplying a charging potential to said cleaning means prior to entranceof said cleaning means into said area of interfering contact, saidcharge potential being sufficient to neutralize charge applied by saidsecond means.